Short Note on Big Bang Theory

The Big Bang Theory is a fundamental concept in astrophysics and hence is very important for the UPSC exam science and technology segment. A lot of research is going on in this field by both Indian and world scientists, to find out exactly how the universe began billions of years ago. In this post, you will read about the Big Bang Theory in brief for the IAS exam.

What is Big Bang Theory?

Big Bang Theory is the accepted model for the origin of the universe. According to this theory, about 1380 crore (13.8 billion) years ago, all matter and energy in the universe were focused into a zone smaller than an atom. At this instant, time, energy, space, and matter were not in existence. This model explains how the universe expanded from a high-density and high-temperature state. This theory also offers explanations for many phenomena such as cosmic microwave background, the existence of light elements in abundance, the large-scale structure and the Hubble’s Law. Measurements regarding the expansion rate of the universe posit the big bang to have happened 13.8 billion years ago and so, this is accepted as the age of our universe.

Two chief assumptions of the Big Bang Model:

The universality of physical laws

The cosmological principle (which states that on large scales the universe is homogeneous and isotropic)

The Big Bang is not considered to be an explosion after which matter pushes outward to fill up an empty universe, but space itself expands over time everywhere.